U.S. patent application number 14/738274 was filed with the patent office on 2015-10-01 for powder based balancing layer.
This patent application is currently assigned to VALINGE INNOVATION AB. The applicant listed for this patent is VALINGE INNOVATION AB. Invention is credited to Niclas HAKANSSON, Jan JACOBSSON, Han PERSSON.
Application Number | 20150275526 14/738274 |
Document ID | / |
Family ID | 47006591 |
Filed Date | 2015-10-01 |
United States Patent
Application |
20150275526 |
Kind Code |
A1 |
PERSSON; Han ; et
al. |
October 1, 2015 |
POWDER BASED BALANCING LAYER
Abstract
A method of manufacturing a building panel with a decorative
surface layer, a core and a balancing and/or protective layer,
wherein the method includes applying a first layer of a first
powder based mix, including wood fibres and a thermosetting binder,
on a core; applying a liquid substance on the first powder based
mix; drying the first powder based mix; turning the core with the
dried first powder based mix such that the first powder based mix
points downwards; applying a second layer on the upper part of the
core; and curing the first and second layers by providing heat and
pressure, wherein the first layer forms the balancing and/or
protective layer and the second layer forms the decorative surface
layer in the building panel.
Inventors: |
PERSSON; Han; (Perstorp,
SE) ; HAKANSSON; Niclas; (Viken, SE) ;
JACOBSSON; Jan; (Landskrona, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VALINGE INNOVATION AB |
Viken |
|
SE |
|
|
Assignee: |
VALINGE INNOVATION AB
Viken
SE
|
Family ID: |
47006591 |
Appl. No.: |
14/738274 |
Filed: |
June 12, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13444653 |
Apr 11, 2012 |
9085905 |
|
|
14738274 |
|
|
|
|
61474498 |
Apr 12, 2011 |
|
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61557734 |
Nov 9, 2011 |
|
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Current U.S.
Class: |
428/535 ;
156/278; 264/128; 427/209; 524/14 |
Current CPC
Class: |
B27N 7/005 20130101;
C08J 2461/28 20130101; E04F 15/045 20130101; C08J 7/042 20130101;
E04F 15/04 20130101; B32B 2607/00 20130101; B05D 1/00 20130101;
B32B 21/02 20130101; B32B 2305/70 20130101; C09D 7/70 20180101;
B32B 2305/07 20130101; B32B 2262/067 20130101; Y10T 428/31982
20150401; C08J 2397/02 20130101; B32B 37/24 20130101; C08J 2497/02
20130101; B32B 2255/24 20130101; B32B 2305/20 20130101; B32B 21/042
20130101; B32B 2317/16 20130101; E04F 13/0866 20130101; B27N 3/06
20130101; B32B 2310/0825 20130101; B32B 2305/30 20130101; B32B
2317/12 20130101; B32B 21/14 20130101; B32B 2471/00 20130101; C09D
5/033 20130101; B27N 3/04 20130101; C09D 161/28 20130101; B32B
2255/08 20130101; E04F 13/10 20130101; B32B 38/145 20130101 |
International
Class: |
E04F 13/10 20060101
E04F013/10; C09D 7/12 20060101 C09D007/12; C09D 161/28 20060101
C09D161/28; C08J 7/04 20060101 C08J007/04; B27N 7/00 20060101
B27N007/00; E04F 15/04 20060101 E04F015/04; B27N 3/04 20060101
B27N003/04; B32B 21/02 20060101 B32B021/02; B32B 21/04 20060101
B32B021/04; B32B 21/14 20060101 B32B021/14; E04F 13/08 20060101
E04F013/08; C09D 5/03 20060101 C09D005/03; B27N 3/06 20060101
B27N003/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2011 |
SE |
1150320-8 |
Nov 9, 2011 |
SE |
1151058-3 |
Claims
1. A method of manufacturing a building panel with a decorative
surface layer, a core and a balancing and/or protective layer,
wherein the method comprises the steps: applying a first layer of a
first powder based mix, comprising wood fibres and a thermosetting
binder, on a core; applying a liquid substance on the first powder
based mix; drying the first powder based mix; turning the core with
the dried first powder based mix such that the first powder based
mix points downwards; applying a second layer on the upper part of
the core; and curing the first and second layers by providing heat
and pressure, wherein the first layer forms the balancing and/or
protective layer and the second layer forms the decorative surface
layer in the building panel.
2. The method as claimed in claim 1, wherein the building panel is
a floor panel.
3. The method as claimed in claim 1, wherein the core is a HDF or
MDF board.
4. The method as claimed in claim 1, wherein the step of applying
said second layer comprises applying a veneer layer.
5. The method as claimed in claim 1, wherein the step of applying
said second layer comprises applying a first paper sheet.
6. The method as claimed in claim 5, wherein the step of applying
said second layer further comprising applying a second paper
sheet.
7. The method as claimed in claim 6, wherein the step of applying
said first and second paper sheets comprises arranging said first
paper sheet such that the fibre direction of the first paper sheet
is extending in a first direction, and arranging said second paper
sheet such that the fibre direction of the second paper sheet is
extending in a second direction, said second direction being
transverse to the first direction.
8. The method as claimed in claim 1, wherein the step of applying
the second layer comprises applying a second powder based mix
comprising wood fibres, binders, and wear resistant particles.
9. The method as claimed in claim 8, wherein the method comprises
the further step of applying a print or a colour substance into the
second mix.
10. A method of manufacturing a building panel with a decorative
surface layer, a core and a balancing and/or protective layer,
wherein the method comprises the steps of: applying a first layer
of a first powder based mix, comprising wood fibres and a
thermosetting binder, on a carrier; placing the core on the first
powder based mix; applying a second layer on the upper part of the
core; and curing the first and second layers by providing heat and
pressure, wherein the first layer forms the balancing and/or
protective layer and the second layer forms the decorative surface
layer of the building panel.
11. The method as claimed in claim 10, wherein the building panel
is a floor panel.
12. The method as claimed in claim 10, wherein the core is a HDF or
MDF board.
13. The method as claimed in claim 10, wherein the carrier is a
fibre based material.
14. The method as claimed in claim 10, wherein the step of applying
said second layer comprises applying a veneer layer.
15. The method as claimed in claim 10, wherein the step of applying
said second layer comprises applying a first paper sheet.
16. The method as claimed in claim 15, wherein the step of applying
said second layer further comprising applying a second paper
sheet.
17. The method as claimed in claim 16, wherein the step of applying
said first and second paper sheet comprises arranging said first
paper sheet such that the fibre direction of the first paper sheet
is extending in a first direction, and arranging said second paper
sheet such that the fibre direction of the second paper sheet is
extending in a second direction, said second direction being
transverse to the first direction.
18. The method as claimed in claim 10, wherein the step of applying
said second layer comprises applying a second powder based mix
comprising wood fibres, binders, and wear resistant particles.
19. A method of manufacturing a separate and continuous powder
based balancing and/or protective layer, which is essentially
uncured, wherein the method comprises the steps of: applying a
powder mix, comprising fibres and a thermosetting binder, on a
carrier, applying moisture on the powder mix such that the powder
mix is connected together to an uncured balancing and/or protective
layer; and releasing the uncured balancing and/or protective layer
from the carrier.
20. The method as claimed in claim 19, wherein the fibres are wood
fibres and the binder a melamine resin.
21. A separate and continuous powder based balancing and/or
protective layer, which is essentially uncured, comprising a powder
mix comprising connected fibres and an essentially uncured
thermosetting binder.
22. The balancing and/or protective layer according to claim 21,
wherein said layer is flexible.
23. The balancing and/or protective layer according to claim 21,
wherein the connected fibres are wood fibres.
24. A building panel, comprising a core, a decorative surface layer
arranged on a first surface of said core, the decorative surface
layer comprising at least one paper layer, and a balancing layer
arranged on a second surface of said core, said second surface
being opposite to said first surface, wherein the balancing layer
is formed of a powder based mix comprising wood fibres and a
thermosetting binder.
25. The method as claimed in claim 10, wherein the carrier is of a
thin material with a thickness that does not exceed the thickness
of the decorative surface layer.
26. The building panel as claimed in claim 24, wherein the core is
a wood-based core.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 13/444,653, filed on Apr. 11, 2012, which
claims the benefit of Swedish Application No. 1150320-8, filed on
Apr. 12, 2011, Swedish Application No. 1151058-3, filed on Nov. 9,
2011, U.S. Provisional Application No. 61/474,498, filed on Apr.
12, 2011, and U.S. Provisional Application No. 61/557,734, filed on
Nov. 9, 2011. The entire contents of each of U.S. application Ser.
No. 13/444,653, Swedish Application No. 1150320-8, Swedish
Application No. 1151058-3, U.S. Provisional Application No.
61/474,498, and U.S. Provisional Application No. 61/557,734 are
hereby incorporated herein by reference.
TECHNICAL FIELD
[0002] The disclosure generally relates to the field of panels with
a decorative surface layer and a balancing and/or protective layer,
preferably floor and wall panels. The disclosure relates to
production methods to produce such panels.
FIELD OF APPLICATION
[0003] Embodiments of the present invention are particularly
suitable for use in production of floating floors, which are formed
of floor panels comprising a core and a decorative wear resistant
solid surface layer comprising fibres, binders and wear resistant
particles that have been applied on the core as a powder as
described in WO 2009/065769. The field of application comprises
products with other types of decorative layers such as paper based,
laminated panels (DPL), where a balancing and/or a protecting layer
is used. The following description of technique, problems of known
systems and objects and features of the embodiments of the
invention will therefore, as a non-restrictive example, be aimed
above all at this field of application and in particular at
floorings which are similar to traditional floating wood fibre
based laminate floorings. The invention does not exclude floors
that are glued down to a sub floor. Embodiments of the invention
can also be used in building panels such as for example wall
panels, ceilings, and furniture components and similar.
BACKGROUND
[0004] Wood fibre based direct pressed laminated flooring (DPL)
usually comprises a core of a 6-12 mm fibre board, a 0.2 mm thick
upper decorative surface layer of laminate and a 0.1-0.2 mm thick
lower balancing and/or protective layer of laminate, plastic, paper
or like material.
[0005] The surface layer of a laminate floor is characterized in
that the decorative and wear properties are generally obtained with
two separate layers one over the other. The decorative layer is
generally a printed paper and the wear layer is a transparent
overlay paper, which comprises small aluminium oxide particles.
[0006] The printed decorative paper and the overlay are impregnated
with melamine formaldehyde resin and laminated to a wood fibre
based core under heat and pressure. The balancing layer is used to
keep the panel flat after production and when the panel is exposed
to variations in moisture conditions that cause the surface layer
to swell and shrink.
[0007] Recently new "paper free" Wood Fibre Floor (WFF) types have
been developed with solid surfaces comprising a substantially
homogenous mix of fibres, binders and wear resistant particles.
[0008] The wear resistant particles are preferably aluminium oxide
particles, the binders are preferably thermosetting resins such as
amino resins and the fibres are preferably wood based. Other
suitable wear resistant materials are for example silica or silicon
carbide. In most applications decorative particles such as for
example colour pigments are included in the homogenous mix. In
general all these materials are preferably applied in dry form as a
mixed powder on a HDF core and cured under heat and pressure to a
0.1-1.0 mm solid layer.
[0009] Several advantages over known technology and especially over
conventional laminate floorings can be obtained: [0010] The wear
resistant surface layer, which is a homogenous mix, can be made
much thicker and a wear resistance is achieved, which is
considerably higher. [0011] New and very advanced decorative
effects can be obtained with deep embossing and by separate
decorative materials, which can be incorporated into the homogenous
surface layer and coordinated with the embossing. [0012] An
increased impact resistance can be reached with a homogenous
surface layer, which is thicker and has a higher density. [0013]
The homogenous surface layer can comprise particles that have a
positive impact on sound and moisture properties. [0014] Production
costs can be reduced since low cost and even recycled materials can
be used and several production steps can be eliminated.
[0015] Powder technology is very suitable to produce solid
decorative surface layer, which are much thicker than conventional
laminate surface layers. Such solid powder based layers create a
much higher tension on the panel when they shrink (or swell) during
curing and balancing is a problem. It is therefore difficult to
produce a panel with a thick and a high quality surface, which is
also well balanced after pressing as well as stable and flat in
variable moisture conditions.
DEFINITION OF SOME TERMS
[0016] By "surface layer" is meant all types of surface layers,
which give the panel its decorative properties and its wear
resistance. By a "WFF mix" is meant a mix of materials comprising
fibres, binders, wear resistant particles and, optionally, a colour
substance, which is preferably applied as powder on a carrier.
[0017] By "WFF floor" is meant a floor panel comprising a solid
surface, which is obtained by a WFF mix that is preferably applied
as dry powder on a core, such as for example HDF, and cured under
heat and pressure.
Known Technique and Problems Thereof
[0018] The new "paper free" WFF floors with a solid surface
comprising a WFF mix of fibres, preferably wood fibres, small, hard
wear resistant particles and a binder are produced according to a
production method where the WFF mix is applied in powder form on a
core. The wood fibres are generally refined, mechanically worked,
and of the same type as used in HDF and particleboard, i.e. treated
in a way that the lignin content is essentially unchanged. They
comprise natural resins such as lignin. The wear resistant
particles are preferably aluminium oxide particles. The surface
layer comprises preferably also colour pigments or other decorative
materials or chemicals. Processed fibres e.g. bleached wood fibres
may also be used. Processed fibres may be semi-transparent, and are
preferably transparent in a cured binder.
[0019] A preferred binder is melamine or urea formaldehyde resin.
Any other binder, preferably synthetic thermosetting or
thermoplastic resins, may be used. The WFF layer is generally
scattered in dry powder form on a wood based core, such as for
example HDF.
[0020] The backside of the core is covered by a balancing layer,
which comprises one or several papers impregnated with melamine
resin in order to get a balanced product after pressing. The panel
is generally produced with a surface that is slightly convex in
order to be able to stay flat even in very dry conditions.
[0021] The total build up with decorative layer, core and balancing
or protective layer is transferred into a press, where the
decorative layer and the balancing or protective layer are cured,
under the influence of heat and pressure.
[0022] By a protective layer is meant a layer adapted to protect
the backside of the core.
[0023] The curing of a melamine formaldehyde (MF) resin involves
shrinkage of the MF resin matrix and the balancing layer is needed
to balance the shrinkage forces from the decorative layer.
[0024] Paper based backer materials can create problems as the
paper always has a dominating fibre direction either in the
production direction or perpendicular to the production direction.
The shrinkage during curing is always higher in the transverse
direction of the fibres as the fibres can be packed together closer
in this direction. The implication of this behavior is that the
balancing layer has different shrinkage in the production direction
compared with the transverse direction.
[0025] As the backer is used to balance the decorative layer, which
may as an example comprise a powder mix with random fibre
direction, the consequence is that an optimized balancing only can
be obtained in one direction, either along or perpendicular to the
production direction. It is also complicated to adapt the thickness
of the paper to different thicknesses of the surface layer.
[0026] However, the paper based balancing layer offer the
advantages that the paper is rather easy to transport together with
the core under the scattering units and into a press.
[0027] It is known from WO 2009/065769 that the balancing layer can
be created with a powder layer that is applied on the backside of
the core. This known disclosure does not show how a powder layer on
a back side of a core should be handled in order to allow a cost
efficient production, especially when discontinuous presses are
used which require that the core with its powder based layers can
be fed in high speed with clamping devices into a press.
[0028] The above description of various known aspects is the
applicants' characterization of such, and is not an admission that
any of the description is prior art.
OBJECTS AND SUMMARY
[0029] An objective of certain embodiments of the invention is to
provide a building panel, preferably a floor panel with a
decorative surface layer and a balancing and/or protective layer
which can be produced in a cost efficient way.
[0030] A first aspect of the invention is a method of manufacturing
a building panel with a decorative surface layer, a core and a
balancing and/or protective layer. The method comprises the steps
below and preferably performed in the listed sequence: [0031]
applying a first layer of a first powder based mix, comprising wood
fibres and a thermosetting binder on a core; [0032] applying a
liquid substance on the first powder based mix; [0033] drying the
first powder based mix; [0034] turning the core with the dried
first powder based mix such that the first powder based mix points
downwards; [0035] applying a second layer on the upper part of the
core; and [0036] curing the first and second layers simultaneously
by providing heat and pressure, wherein the first layer forms the
balancing and/or protective layer and the second layer forms the
decorative surface layer in the building panel.
[0037] The method offers the advantages that a powder based
balancing or protective layer can be applied in a cost efficient
way by scattering on a core. The powder may be fixed to the core
with a liquid substance that swells, partly dissolves or dissolves
the resin, thereby making the powder tacky and stick together. A
drying step removes part of the water thus leaving the powder glued
not only to itself but also to the core. The attachment makes the
first layer stable such that the core with the first layer can be
turned and fed under scattering units and into a press. A paper
based balancing or protective layer can be replaced in a cost
efficient way by a wood fibre based layer with random fibre
direction that has similar shrinkage properties as the decorative
surface layer.
[0038] The building panel may be a floor panel.
[0039] The core may be a HDF or MDF board.
[0040] The second layer may comprise a veneer layer. Thereby, the
veneer layer forms the decorative surface layer. The second layer
may comprise a sheet-shaped layer of wood. A curable lacquer may be
applied on top of the veneer layer.
[0041] The second layer may comprise a first paper sheet. In this
embodiment, the second layer forming the decorative surface layer
is a laminate such as a DPL (direct pressed laminate) or HPL (high
pressure laminate).
[0042] The second layer may further comprise a second paper
sheet.
[0043] The first and/or the second paper sheet may be impregnated
with a thermosetting resin such as melamine formaldehyde.
[0044] The first paper sheet may be arranged such that the fibre
direction of the first paper sheet is extending in a first
direction, and the second paper sheet may be arranged such that the
fibre direction of the second paper sheet is extending in a second
direction, said second direction being transverse to the first
direction.
[0045] The second layer may comprise a second powder based mix
comprising wood fibres, binders, preferably a thermosetting binder,
and wear resistant particles. Thereby, the second layer can be
applied in the same way as the powder based balance or protective
layer by scattering on the core.
[0046] The method may comprise the further step of applying a print
or a colour substance into the second mix.
[0047] A second aspect of the invention is a method of
manufacturing a building panel with a decorative surface layer, a
core and a balancing and/or protective layer. The method comprises
the steps below and is preferably performed in the listed sequence:
[0048] applying a first layer of a first powder based mix,
comprising wood fibres and a thermosetting binder on a carrier,
preferably of a thin material with a thickness that does not exceed
the thickness of the decorative surface layer; [0049] placing the
core material on the first powder based mix; [0050] applying a
second layer on the upper part of the core; and [0051] curing the
first and second layers by providing heat and pressure wherein the
first layer forms the balancing and/or protective layer and the
second layer forms the decorative surface layer of the building
panel.
[0052] The method offers the advantages that a powder based
balancing or protective layer can be applied in a cost efficient
way by scattering on a carrier that keeps the powder based
balancing or protective layer connected to the core during
transport to the device that applies the surface layer and finally
when the core is fed into the press.
[0053] The building panel may be a floor panel.
[0054] The core may be a HDF or MDF board.
[0055] The carrier may be a fibre based material.
[0056] The second layer may comprise a veneer layer. Thereby, the
veneer layer forms the decorative surface layer. A curable lacquer
or powder mix layer may be applied on top of the veneer layer.
[0057] The second layer may comprise a first paper sheet. In this
embodiment, the second layer forming the decorative layer is a
laminate such as a DPL (direct pressed laminate) or HPL (high
pressure laminate).
[0058] The second layer may further comprise a second paper
sheet.
[0059] The first and/or the second paper sheet may be impregnated
with a thermosetting resin such as melamine formaldehyde.
[0060] The first paper sheet may be arranged such that the fibre
direction of the first paper sheet is extending in a first
direction, and the second paper sheet may be arranged such that the
fibre direction of the second paper sheet is extending in a second
direction, said second direction being transverse to the first
direction.
[0061] The second layer may comprise a second powder based mix
comprising wood fibres, binders, preferably a thermosetting binder,
and wear resistant particles. Thereby, the second layer can be
applied in the same way as the powder based balance or protective
layer by scattering on a core.
[0062] The method may comprise the further step of applying a print
or a colour substance into the second mix.
[0063] A third aspect of the invention is a method of manufacturing
a separate and continuous powder based balancing and/or protective
layer, which is essentially uncured. The method comprises the steps
below and is preferably performed in the listed sequence: [0064]
applying a powder mix comprising fibres and a thermosetting binder
on a carrier; [0065] applying moisture on the powder mix such that
the powder mix is connected together to an essential uncured
balancing and/or protective layer; and [0066] releasing the uncured
balancing and/or protective layer from the carrier.
[0067] The separate and continuous powder based balancing or
protective layer may be used in a method for producing a building
panel which method comprises the steps below and is preferably
performed in the listed sequence: [0068] placing the uncured
balancing and/or protective layer under a core material; [0069]
applying a surface layer on the core material; and [0070] curing
the surface layer and the uncured balancing and/or protective layer
under heat and pressure.
[0071] The method offers the advantages that a powder based
balancing or protective layer can be produced as a separate uncured
layer that can be handled as a conventional paper based balancing
or protective layer. The moisture, that preferably comprises water,
may be sprayed on the powder such that the binder, preferably a
melamine resin, moisture swells, partly dissolves or dissolve the
resin, thereby making the powder tacky and stick together. The
fibres in the mix will be connected to each other when the water
dries. The fibres may also be connected by applying heat, e.g., IR
heating, thereby removing the moisture and connecting the fibres in
the mix. A powder based uncured balancing or protective layer may
be formed as a flexible thin sheet and a core material may be
placed over the balancing or protective layer.
[0072] The surface layer may comprise a powder based surface layer,
at least one paper sheet or a veneer layer.
[0073] A fourth aspect of the invention is a separate and
continuous powder based balancing and/or protective layer, which is
essentially uncured. The separate layer comprises powder mix
comprising connected fibres and an essentially uncured
thermosetting binder.
[0074] The powder based balancing or protective layer is preferably
produced according to the method of the third aspect.
[0075] A fifth aspect of the invention is a building panel,
comprising a core, preferably a wood-based core such as MDF or HDF
board, a decorative surface layer arranged on a first surface of
said core, the decorative surface layer comprising at least one
paper layer, and a balancing layer arranged on a second surface of
said core, said second surface being opposite to said first
surface, wherein the balancing layer is formed of a powder based
mix comprising wood fibres and a thermosetting binder.
[0076] The building panel is preferably produced according to the
first or second aspect of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0077] The invention will in the following be described in
connection to preferred embodiments and in greater detail with
reference to the appended exemplary drawings, wherein,
[0078] FIGS. 1a-e illustrate a method to form a balancing and/or
protective layer.
[0079] FIGS. 2a-e illustrate a method to form a balancing and/or
protective layer.
[0080] FIG. 3 illustrates a building panel wherein the decorative
layer is laminate.
[0081] FIG. 4 illustrates a building panel wherein the decorative
layer is a veneer layer.
DETAILED DESCRIPTION OF EMBODIMENTS
[0082] The powder intended to be used as a balancing and/or
protective layer 3 is applied as a first powder mix on a core 2,
preferably a MDF or HDF material, preferably by one or several
scattering units 11 as shown in FIG. 1a. FIG. 1b shows that the
powder is thereafter pre-stabilized by a fluid 7, preferable based
on water, which is applied by a stabilizing device 9. The first
powder layer is thereafter dried. Such drying can be performed
off-line in a controlled environment or in-line by applying heat 8
with a heating device 10 on the powder mix 3. The heating device 10
may comprise infrared light. The water based fluid 7 and the
following drying 8, attaches the powder layer 3 to the core 2, to
such an extent that the core 2 with the powder can be turned
180.degree. to bring the powder based balancing or protective layer
3 downwards, as shown in FIG. 1c, such that it may be transported
further along the production line or be stacked on a pallet for
intermediate storage before further production takes place.
[0083] Oversized or undersized fibres from the hammer mill that
produces the fibres for the surface layer may be used in the
balancing or protective layer mix. The fibre size is not as
critical as in a powder based surface layer and may vary from a
fibre length of several mm to less than 0.1 mm. The most preferred
average fibre length is 0.1-1.0 mm.
[0084] A second powder based surface layer mix 1 is thereafter
applied on the upper side of the core 2 as showed in FIG. 1d. A
digital print 4 may be printed into the surface layer 1. The
surface layer 1 preferably also comprises wood fibres, a colour
substance, thermosetting binders and aluminium oxide particles.
[0085] The wood fibres in both the first and second powder mixes in
all embodiments of the invention may be virgin, unrefined, refined
and/or processed, comprising lignin and without lignin, e.g.
.alpha.-cellulose fibres or holocellulose. A mixture of refined and
unrefined fibres may also be used. It is also contemplated that
vegetable fibres as jute, linen, flax, cotton, hemp, bamboo,
bagasse and sisal may be used. Also mineral fibres and carbon
fibres may be used.
[0086] As an alternative to the second powder based surface layer
mix, the second layer forming the decorative surface layer may
comprise at least one paper sheet 21 adapted to form a laminate,
which is shown in FIG. 3. Said at least one paper sheet 21 may be
arranged on the upper side of the core. Preferably, the second
layer comprises a first paper sheet 21 and a second paper sheet 22.
The first and second paper sheets 21, 22 may be arranged such that
the fibre direction of the first paper sheet 21 is extending in a
first direction, and the fibre direction of the second paper sheet
22 is extending in a second direction being opposite to the first
direction. By arranging the fibre direction of the sheets
transversely, the second layer has fibre directions in more than
one direction. Thereby, during shrinkage, the second layer obtains
properties more similar to the balancing or protective layer having
a random fibre direction compared to a surface layer having only
one dominating fibre direction.
[0087] The first paper sheet 21 may be a printed paper. The second
paper sheet 22 may be a transparent overlay paper. The second paper
sheet 22 may form a wear layer and may comprise small aluminium
oxide particles. The first and second paper sheets 21, 22 may be
impregnated with melamine resin such that they can be laminated to
the core under heat and pressure simultaneously as curing the
balancing and/or protective layer. The second paper sheet 22 may be
arranged on top of the first paper sheet 21.
[0088] Alternatively, the second layer may comprise a veneer layer
23 or sheet-shaped layer of wood arranged on the upper side of the
core, which is shown in FIG. 4. The second layer may further
comprise a curable lacquer layer applied on top of the veneer layer
or sheet-shaped layer of wood. The curable lacquer layer may be
cured simultaneously as curing the balancing and/or protective
layer.
[0089] Other decor layers may also be used as a second layer, such
as cork, rubber, plastics, especially a thermoplastic decor
layer.
[0090] The core 2 with the surface layer 1 and the balancing or
protective layer 3 is thereafter fed into a press where the layers
are cured under heat and pressure. The balancing layer may be
optimized in thickness and material composition in order to create
a perfect balancing of the surface layer. The fibre orientation in
the layers may be essentially the same.
[0091] Recycled fibres from the machining of the panels, for
example when a mechanical locking system is formed, may be used in
the balancing or protective layer mix.
[0092] The balancing or protective layer 3 may preferably comprise
a homogenous powder mixture comprising about 50 weight % recycled
MDF fibres with a moisture content of preferably 3-8% and about 50
weight % Melamine Formaldehyde (MF) resin (Prefere 4865, Dynea).
The MF resin amount can vary between 30-70 w-%, preferably 40-65
w-% and most preferably 45-60 w-%. The fibre content may vary from
30-70%, most preferably between 40-55%.
[0093] If needed the powder formulation can be modified such that
thermosetting particles, pigments, hard particles, release agents,
wetting agents and similar materials are included into the mix. The
thermosetting plastic particles may be mixed at random into the
powder or applied as a separate thin layer and may be used to
provide a sealing against moisture penetration into the core.
[0094] The core of an HDF board preferably has a moisture content
of 0-8%.
[0095] The scattering unit 11 may have capacity of scattering of
100-1000 g/m.sup.2 with a tolerance of +/-5% as measured using a
calibration cup with an area of 100.times.100 mm cross- and length
wise the board. The amount of stabilization fluid may vary from 0
up to 200 g/m.sup.2.
[0096] The scattering unit 11 may comprise a needle belt and a
scattering roller 12. The scattering roller is provided with
needles in the range of about 30-120, preferably about 50-100, and
most preferably about 70-90 needles per cm.sup.2. The needle length
is about 0.5-2.5 mm, preferably about 1-2 mm and most preferably
about 1.5 mm. Several scattering units 11 may be used to even out
differences in the applied powder mixture.
[0097] Furthermore, the scattering unit may be provided with a
needle belt with needles with a preferred length of about 15-20 mm,
a preferred frequency in the range of about 500-1000 rpm preferably
about 1000 rpm, and a stroke length of about +/-3 mm.
[0098] The stabilizing device 9 and the heating device 10 may be
used to stabilize the surface layer 1 and/or the balancing or
protective layer 3.
[0099] The stabilization device 9 may stabilize the powder using
steam, nozzle spray coating or ultra-sonic spray coating.
[0100] Stabilization fluid may comprise solvents such as non-polar
solvents, polar aprotic solvents and polar protic solvents or
mixtures thereof. Preferred solvents are polar protic solvents such
as isopropanol, ethanol and water. Most preferred is water.
[0101] The stabilization fluid can further comprise additives such
as wetting agents, defoamers, release agents, anti-slip agents and
catalysts.
[0102] FIGS. 2a-2e show how a powder based balancing or protective
layer can be applied by applying the powder based balancing or
protective layer as a first mix 3 on a carrier 5. The core is
applied on the mix (FIG. 2c) and a powder based surface layer 1 is
applied on the core 2. Alternatively, a surface layer of at least
one paper sheet 21 or veneer layer 23 is applied to the core for
forming a decorative surface layer, as described above with
reference to FIGS. 3 and 4. Stabilizing and/or heating of the
balancing and/or surface layers may be made as described above. The
core and layers are fed into a press and cured under heat and
pressure to a building panel as shown in FIG. 2e.
[0103] The carrier may be a paper with a weight of for example
100-200 gr. It may also be a non-woven fibre based material or a
foil.
[0104] Powder may also be applied on a carrier that preferably is a
conveyor belt 11 and stabilized with fluid and dried such that it
can be released from the conveyor 11 and handled as a separate
sheet without the carrier 5 as shown in FIG. 2b. Such a separate
and continuous sheet or layer is essentially uncured. The sheet or
layer may be flexible such that it may be bent. The powder may
comprise fibres, preferably wood fibres, and a thermosetting
binder.
EXAMPLES
[0105] In example 1 below the powder formulation for the balancing
layer used comprising 50 weight-% recycled MDF fibre (Valinge
Innovation Sweden), 50 weight-% Melamine Formaldehyde resin
(Prefere 4865, Dynea).
Example 1
Powder Based Product Obtained Through Heat Compression of Product
Produced with Powder Based Balancing Layer and a Treated Powder as
Decorative Layer
[0106] A balancing layer was formed by scattering 500 g/m.sup.2 of
powder on a 9.7 mm HDF core. 40 g/m.sup.2 of stabilization fluid
with 5 w-% wetting agent, 6 w-% release agent and 3 w-% catalyst
was applied by spraying on the powder based balancing layer mix
[0107] The powder and the stabilization fluid were applied at a
line speed of 2.7 m/min. The powder based balancing layer was dried
at the same line speed with IR with an effect of 19 kW.
[0108] The resulting intermediate product with a stabilized powder
based balancing layer was turned 180.degree. and stacked on a
pallet before use in the next operation where a decorative surface
layer of 500 gr/m.sup.2 was applied in powder form on the core.
[0109] The core with the surface and balancing layers was pressed
in a press with a pressure of 40 kg/cm.sup.2, during 25 seconds.
The upper press table applied a heat of 170 degrees C. on the
surface layer and the lower press table applied a heat of 175
degrees C. on balancing layer.
[0110] A panel with a small pre tension backwards and a slightly
convex surface was obtained.
[0111] In example 2 below the powder formulation for the balancing
layer used comprising 42 weight-% recycled MDF fibre (Valinge
Innovation Sweden), 58 weight-% Melamine Formaldehyde resin
(Prefere 4865, Dynea).
Example 2
Powder Based Product Obtained Through Heat Compression of Product
Produced with Powder Based Balancing Layer and a Treated Powder as
Decorative Layer
[0112] A balancing layer was formed by scattering 320 g/m.sup.2 of
powder on a 9.7 mm HDF core.
[0113] 40 g/m.sup.2 of stabilization fluid with 1 wt-% wetting
agent, 6 wt-% rerelease agent and 1 wt-% catalyst was applied by
spraying on the powder based balancing layer mix
[0114] The powder and the stabilization fluid were applied at a
line speed of 2.0 m/min. The powder based balancing layer was dried
at the same line speed with IR with an effect of 19 kW.
[0115] The resulting intermediate product with a stabilized powder
based balancing layer was turned 180.degree. and feed into the next
operation where a decorative surface layer of 550 gr/m.sup.2 was
applied in powder form on the core.
[0116] The core with the surface and balancing layers was pressed
in a press with a pressure of 40 kg/cm.sup.2, during 37 seconds.
The upper press table applied a heat of 184.degree. C. on the
surface layer and the lower press table applied a heat of
175.degree. C. on balancing layer.
[0117] A panel with a small pre tension backwards and a slightly
convex surface was obtained.
[0118] It is contemplated that there are numerous modifications of
the embodiments described herein, which are still within the scope
of the invention as defined by the appended claims.
[0119] For example, it is contemplated that the balancing layer may
be provided with an orientation in some embodiments. The wood
fibres based the balancing layer generally has a random fibre
direction. However, in order to form a balancing layer having
similar properties as the decorative surface layer, an orientation
may be formed in the balancing layer. Such orientation may be
provided with by means of scattering the powder in a specific
pattern, by a pattern in the press plate, or by means of a rake
forming a pattern.
[0120] The steps of the method claims do not necessarily have to be
performed in the above described order. It is for example
contemplated that the second layer may be applied before the first
layer, and that the core is turned after the second layer has been
applied. Thereafter the first layer is applied, liquid is applied,
the first powder based mix is dried and the core is turned with the
dried first powder based mix such that the first powder based mix
points downwards.
* * * * *